In ITU-T protocols H.248 and Q.1950 the control of so-called media gateways (MGWs=switching devices in particular in a cellular mobile radio network or fixed network) is specified by so-called media gateway controllers (MGCs). The protocol Q.1950 is used in conjunction with the BICC protocol Q.1902.4 also specified by the ITU-T. These protocols can also be used for 3GPP applications. Media gateways for example connect user connection sections (for the transmission of user data such as voice, text, multimedia) of a telecommunication network and in some instances convert different codings, e.g. voice codings such as G.711 or AMR, to each other. User connection section termination, abbreviated to termination, refers below to the termination of a section of a user connection switched through the MGW, e.g. for voice or multimedia (sound and image) at this MGW. The MGW sends and/or receives (user) data associated with the user connection through said termination. In the parlance of the protocols H.248 and Q.1950 a so-called termination corresponds to a user connection section termination.
The above-mentioned protocols allow existing user connections to be modified, e.g. by selecting a different coding. The signaling thereby used between MGC and MGW (protocols H.248 and Q.1950) is such that each termination into the MGW is modified irrespective of the other terminations connected to it within the MGW. For example the MGW can be instructed to use a different coding at this termination or to send and/or receive no data. When a termination is modified, the MGW does not know whether other connections also connected by it to said termination will also be modified later. Therefore when a termination is modified the MGW must immediately implement measures if different codings result in connected terminations (in the parlance of the protocols H.248 and Q.1950 interconnected terminations are located within an MGW in a so-called common context) and these are converted to each other for example by so-called transcoding. In specific cases however the coding of all terminations interconnected into the MGW, which are in the same context, should be modified almost simultaneously, for example in the context of the so-called BICC codec modification or codec renegotiation (see Q.1902.4), by means of which the coding of existing voice connections can be modified. The 3GPP also uses the said BICC procedures to switch existing user connections between voice and multimedia (i.e. a combination of voice and image in a common coding). The MGC can identify such situations based on the so-called call control signaling coming into it, e.g. Q.1902.4. As the signaling of the MGC to the MGW is sequential, in the event of almost simultaneous switching of all connected terminations within an MGW a possibly unwanted response results. The MGW briefly activates a transcoder, which is then almost immediately deactivated again. This generates an unnecessary workload in an MGW and reduces its throughput. It would be acceptable but has hitherto not been technically possible to break the connection for a short time. When the first termination is modified, the MGW may also determine that it cannot convert the new coding of this termination into the coding still used at the other termination(s). This can happen for example when switching between a voice connection and a multimedia connection or a general data connection. In this case the MGW therefore rejects the modification of the user connection via H.248/Q.1950 signaling.